For 2 months now I've had a little clear blister like pocket (situated on the inside if my bottom eyelid) that seems to fill with pus every 2-3 weeks, then the pus drains and the pocket goes clear again. It's not uncomfortable, nor has it been sore.

I've been to the doctors, had blood tests and eye examinations, all of which have come back fine, so I've nothing sinister. I've been given instructions to hold a warm cloth for 10 minutes per day to the said eyelid as antibiotics won't clear it. My question, how long does these things take to clear up?